OpenGL ES 2.0渲染为多个纹理

Question

我正在使用OpenGL ES 2.0构建iPad应用程序。我需要做的是渲染多个纹理，然后渲染所有纹理进行查看。我使用基于用户触摸位置的GL_POINTS进行绘制。我的代码，我现在已经是：

生成帧缓冲，纹理和渲染缓存：

glGenFramebuffers(1, &viewFramebuffer); 
glGenRenderbuffers(1, &viewRenderbuffer); 
glBindFramebuffer(GL_FRAMEBUFFER, viewFramebuffer); 
glBindRenderbuffer(GL_RENDERBUFFER, viewRenderbuffer); 

glGenTextures(1, layers); 
glBindTexture(GL_TEXTURE_2D, layers[0]); 
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); 
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); 
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); 
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); 
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, self.bounds.size.width, self.bounds.size.height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL); 
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, layers[0], 0); 

抽奖：

glBindFramebufferOES(GL_FRAMEBUFFER_OES, viewFramebuffer); 
.... 
glDrawArrays(GL_POINTS, 0, (int)vertexCount); 
glBindRenderbuffer(GL_RENDERBUFFER, viewRenderbuffer); 
[context presentRenderbuffer:GL_RENDERBUFFER]; 

上述工程OK，但是当我想渲染到我的应用程序停止绘制任何新内容的新纹理。我绑定这样的新纹理：

glGenTextures(1, &layers[1]); 
glBindTexture(GL_TEXTURE_2D, layers[1]); 
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); 
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); 
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); 
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); 
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, self.bounds.size.width, self.bounds.size.height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL); 
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, layers[1], 0); 

然后再次调用绘图方法。我的代码在渲染到第一个纹理时起作用，但当我尝试生成要渲染的新纹理时，应用程序停止绘制。任何人都可以帮忙吗？

Answer 1

我让我的代码工作。我的framebuffers没有正确生成，并且我的纹理没有准确绑定，所以出现了一些问题。了解到的经验 - 总是在生成后检查frameBuffer的状态！在这里它是：

设置帧缓冲区：

// Generate textureFrameBuffer for handling drawing to textures 
glGenFramebuffers(1, &textureFrameBuffer); 
glBindFramebuffer(GL_FRAMEBUFFER, textureFrameBuffer); 

// Generate renderBufferer for drawing to screen 
glGenRenderbuffers(1, &viewRenderbuffer); 
glBindRenderbuffer(GL_RENDERBUFFER, viewRenderbuffer); 
[context renderbufferStorage:GL_RENDERBUFFER fromDrawable:(id<EAGLDrawable>)self.layer]; 
glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_WIDTH, &backingWidth); 
glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_HEIGHT, &backingHeight); 

//Generate first texture and bind to textureFrameBuffer 
glGenTextures(1, &layers[0]); 
glBindTexture(GL_TEXTURE_2D, layers[0]); 
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, backingWidth, backingHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL); 
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); 
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); 
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); 
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); 
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, layers[0], 0); 

//check if frameBuffer is OK 
if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE){ 
    NSLog(@"failed to make complete framebuffer objects %x", glCheckFramebufferStatus(GL_FRAMEBUFFER)); 
    return NO; 
} 

//Generate viewFrameBuffer for drawing to view 
glGenFramebuffers(1, &viewFramebuffer); 
glBindFramebuffer(GL_FRAMEBUFFER, viewFramebuffer); 
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, viewRenderbuffer); 

if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) 
{ 
    NSLog(@"failed to make complete framebuffer object %x", glCheckFramebufferStatus(GL_FRAMEBUFFER)); 
} 

要绘制到第一纹理：

glBindFramebuffer(GL_FRAMEBUFFER, textureFrameBuffer); 
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, layers[0], 0); 
.... 
glDrawArrays(GL_POINTS, 0, (int)vertexCount); 

要生成和结合第二纹理：

glGenTextures(1, &layers[1]); 
glBindFramebuffer(GL_FRAMEBUFFER, textureFrameBuffer); 
glBindTexture(GL_TEXTURE_2D, layers[1]); 
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); 
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); 
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); 
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); 
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, backingWidth, backingHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL); 
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, layers[1], 0); 

绘制到第二纹理：

glBindFramebuffer(GL_FRAMEBUFFER, textureFrameBuffer); 
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, layers[1], 0); 
.... 
glDrawArrays(GL_POINTS, 0, (int)vertexCount); 

提请所有材质屏幕：

// Bind view buffer 
glBindFramebuffer(GL_FRAMEBUFFER, viewFramebuffer); 
//clear screen every frame 
glClear(GL_COLOR_BUFFER_BIT); 
//bind layer texture 
for (int i=0; i<= layerCount; i++) { 
    glBindTexture(GL_TEXTURE_2D, layers [i]); 
    .... 
    glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); 
} 

[context presentRenderbuffer:viewFramebuffer];